The present invention relates to mail tray loading devices used for automatically loading mail into mail trays. The mail tray loader is designed to eliminate the need for manual intervention during the tray loading process. The mail tray loader is also designed to reduce the cost and complexity found in present tray loading machinery. In a typical inserting machine installation, the envelopes exiting the inserting machine (inserter) are transferred from the inserter onto a low-speed conveyor on which the envelopes accumulate in a shingled stream. Transfer of mail from this conveyor to the mail tray is usually accomplished manually. This tends to stifle productivity, particularly in high-volume operations. Although some automatic traying machines exist, they are relatively complicated and expensive. The present invention replaces the traditional output conveyor and offers a compact and cost-effective means for loading the mail into trays automatically.